First of all, Id like to thank Matt (xtremers) for making me a downpipe and test pipe. Very nice product, and fit excellent. Thank you Matt! :cheers

After installing the DP and TP, I drove my car for the first time in a month and a half. Drove around and noticed some things I didnt like. First... the exhaust made weird noises. When still in gear, I let off the gas and thats when it made those noises. Not backfiring, but kinda poof poof poof poof. You know what im talking about. So I filled it up with new gas and changed the spark plugs. Its barely still there, but improved alot. Ill live with that. But heres the more important problem.....

Overboost. I dont and cant have it on my stock block. I went out on the highway and opened it up. Noticed a couple things. Going about 60mph in 4th gear, boost goes up from 8-10psi and my fuel goes up to around 80psi. But if im doing the same speed and have it in 3rd gear, floor it, my boost goes up to 12psi! Not sure if it was still climbing cuz I let off as soon as I seen that. NOT GOOD. I dont need to blow my motor. So..... whats goin on with that? Any suggestions?

I know before this, my max psi was 7-8, and fuel went up to 70pi.



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

do you got a boost controller? if so what kind? that might be it. check your vacuum lines etc.
Michael
99gs HRC Stage IV 8-Injector Setup
2GNT Member #32

you opened a restriction up and now it wants to boost more/easier. i believe you can get a good boost controller to fix the problems.

My exaust makes the same noise, Usually after boosting hard. I have a straight pipe with a resinator type muffler.

I believe the higher flowing downpipe and test pipe setup allows the turbo to spool up much quicker. It will seem like a boost spike or surge. At this point, you'll probably want to turn down the boost level by 1-2 psi to compensate for the higher boost level that is achieved from the better exhaust setup. This is proof that the exhaust setup works!! Now, you can thank XtremeRS again :thumbsup

no, i do not have a boost controller.



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

Glad to hear the install went good :thumbsup The exhaust sounds you speak of are very normal, esp when you dont have a cat converter. It sounds like mini backfires sort off..like a gurgling of the exhaust note.. As for the boost spike- do you have a manual boost controller? If so, then check that out. Check all your vac lines, esp the one going to your wastegate actuator. You could have a boost leak somewhere also, so double check all your hose clamps, and all that. I did notice when upgrading to a larger DP, I could build a pound or two more boost with the previous boost control setting..it's just flowing better :) If your previous setting was 8 psi, and you saw 12 psi, then something else isn't right...Check for any kind of vac line or boost line leaks first..

but if the boost goes back down once the spike is over, how would he go about getting the full potential of the kit AND not worry about the spiking? if he turns it down and the spike goes back down to the WG setting, he will be a few psi less than he is running now when he should be putting out more. his spike would be what he is running all the time now and then it goes down and he is slower. no one wants that. :-)

Originally posted by Diceman19
but if the boost goes back down once the spike is over, how would he go about getting the full potential of the kit AND not worry about the spiking? if he turns it down and the spike goes back down to the WG setting, he will be a few psi less than he is running now when he should be putting out more. his spike would be what he is running all the time now and then it goes down and he is slower. no one wants that. :-)

You can also try to hook up the wastegate boost line to the intake manifold, rather than where its at now, on the compressor. This way, you will get manifold boost pressure, not compressor boost pressure(this can be different if you have small leaks). This usually works better for when you have a MBC setup though. I had the same problem with spiking, but moving the wastegate line to the intake mani solved my issue. I took the brake booster vac line, cut it, and put in a T, then ran the new line to the wastegate actuator. I used small hose clamps too on the T fitting, because you really dont want those to blow off for some reason, and have no power brake assist :o

Originally posted by Diceman19
but if the boost goes back down once the spike is over, how would he go about getting the full potential of the kit AND not worry about the spiking? if he turns it down and the spike goes back down to the WG setting, he will be a few psi less than he is running now when he should be putting out more. his spike would be what he is running all the time now and then it goes down and he is slower. no one wants that. :-)

True

:-) That is if it's just a spike. I thought he mentioned that boost climbed. From personal experience, with a higher flowing exhaust, the increased boost of 1-2 psi is there throughout the long pull--not just surging. When he was doing the 3rd gear pull, there was more boost surge because a higher load can be achieved in 3rd, but after that "spike," boost will still be 1-2 psi higher than what he has set (7-8 psi.) The problem could be this: The spike itself will probably not hurt anything, because it is so quick. However, if his fuel setup is fine tuned to 7-8 psi, and the better flowing exhaust nets an additional 1-2 psi, it could just put him in the gray area of being in optimal air/fuel or a tad bit towards the leaner side. Thus, the reasoning for wanting to lower his boost level by 1-2; or, he could just adjust his air/fuel to compensate for the extra boost--if he wants to run 8-10 psi daily.

:D

thanks for the commments so far. the boost didnt spike, it just kept rising. 10.....11....12.... o shit! haha ill have to try what matt suggested about T'ing off the mani (collente also suggested this). so ill probably do that tomorrow since no one is open today, and see how it goes. hopefully that will fix it.



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

What you are describing is not a boost spike. It's called boost creep. I highly doubt that the downpipe has anything to do with your problem.

^ what do u suggest i do?



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

ok. i did what they suggested, and ran the hose from the wastegate T'd into the same line my boost gauge and bov is on and capped the turbo. took it out for a drive, and the highest it went was 10psi. which is alot better than the 12psi i hit, but id still like it to be 1-2psi less. but its better than before, so that will work. thanks guys. :thumbsup

btw..... damn my car spools sooo much faster now, even gave me an extra couple psi. wOoT! i just hope i dont blow it up. haha



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

you can adjust the wastegate by +-2psi. i *think* you screw the arm counter clockwise to turn it down.. i did this, but a while ago. i still think there's something else wrong though.

well..... after driving around yesterday, i went to autozone to see if i had any new cel's. i have 4 of them now. 3 of them dont bother me, but 1 of them is P0172. which is the fuel system for bank 1 was too rich. huh?? i previously added more fuel because i was boosting more. so i went driving some more, and boost hit 12psi again. x( so i dont know what to do. i thought i fixed it, but i guess not. AH!

u guys think its time to invest in a boost controller? i know its not a good idea on a stock block incase u want to turn it up. but trust me, i can control myself. ill just turn it so i have it to what my wastegate should open at. i want to run at the max right now, 9psi. no creeping or spiking. just less than 10. im worried my motor might go boom. or..... i could just no get on it anymore, but thats no fun. thats why i bought all the shit ive bought, to go faster.



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

yeah man, it's your wastegate, turned that bitch down. and you're too rich if that code comes up. if you have a SAFC lean it out some till you have your reading at .97 at WOT.

you may port your wastegate and install a 34mm flapper, that will eliminate your boost creep. if you want to spend some money, get an external dump. :thumbsup

i dunno. i might stop by summit racing on the way home and pick up a turboxs high performance boost controller. ill see if that helps.

i noticed my turbo sounds like a friggin jet now. and my bov sounds louder and different now. it makes a quick zip before it blows off. kinda like..... zip pssssssssh. maybe like the air is coming out too fast now?



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

it is. :thumbsup

what size is the dp that x made? im interested in one.

DWAYNE H
1996 eclipse
under construction widebody eclipse, targa top, 19inch rollers, big brakes, 10 point custom cage, frank 2.4 hrc s20g turbo, custom marble paint job

2000 Yamaha R-1, 165rwhp 117 ftlbs tq

^ its 2.5". maybe too small for u? didnt u post something about getting a 3.75" exhaust or something like that?



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

I guess i can join the club with you, i also get high boost readings when flooring it in 3rd and 4th. Mine goes up to about 11-12, but i let off so it wont blow anything, i have no clue as to what this is. I have not gotten this car to run right since August, for some strange ass reason, i spool up at 4500rpm and dont reach 8-9 psi until right before redline, i wish my car ran like yours and that was the only problem i had, i am trying to get everything staright or i am selling my turbo stuff and just buying a kit.

I dont think my mbc is helping. Boost went up to 11-12psi today. I dunno what to do. I dont know what it is. I tried everything u guys said.



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

another update - went driving tonight, and i hit 15psi. wtf? then other times it wont go over 9. something is wrong, but i dont know what. i cant figure out how to fix this. starting to think my WG is drunk.

and i checked my compression today just for the hell of it, and my numbers are still good about 208 across the board. so looks like all the abuse and spiking my car has gone through, its still holding up. so thats good.



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

port your WG. ;-) that may be the only other option. get the 34mm flapper. if that doesnt work, get back that new block and rebuild. :-)

I am having the same problems you are, i hope someone can help us fix it. I also think my wastegate is messed up, but then again i have it touching my oil drain line and i think it may be b/c of that for my problem, i wish i could help, but i am on the same boat you are on. Please someone more suggestions. Thanks

man, Ok I'll help you guys out. Get a smaller WG spring and use the manual boost controller to increase boost back up to 10psi. PROBLEM SOLVED:thumbsup

You shouldn't be having such large spikes just because you installed those new parts...

And I have a standard Big 16G WG in my turbo and I dont ever see any spikes like you are reporting... somthing must be meseed up somewhere....

Whats your vac line routing like??? I've seen some weird mbc line routing that can cause strange things to happen....

Hmmm, after everything that you've tried, I'm also leaning towards the wastegate, too. It's not a very common problem, but I guess it could happen. Which wastegate do you have? If you have a wastegate stronger than the 5psi unit, you might want to get the 5psi piece and just use your MBC to turn it to your target boost level of 7-8 psi. For instance, if you have a 10psi wastegate, you wouldn't be able to use the MBC to decrease the boost level to below 10psi. But then, let's say you have an 8 psi actuator (and it's fualty) and you set the MBC to 8psi, your boost level should still be at about 8psi. If this is what you've done, then I'd look very closely at your mbc/boost vac lines or hookup. Be patient and keep checking:-)

Yea, I think its probably my WG. Because before I even bought the mbc, it would creep. I searched on here and then went over to another dsm site, and seems like boost creep is somewhat common with using a larger exhaust and not much boost. So..... Im thinking that I might just wait it out to do anything and just be carefull not to boost the hell out of my car. Then when I get my re-built engine in there, turn up the boost and see how it responds with creeping. I think I might be ok once I turn it up. If not, then Ill probably get the bigger flapper and start porting. We'll see.



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown

I've read many 4G63 guys with external wastegated turbos running 3" downpipes and/or catbacks experience boost creep, and supposedly, internally gated turbos are supposed to minimize or eliminate that problem--which is why HRC primarily sells internal wastegate turbos. What kind of turbo do you have??

I have the s16g. That what I was reading about too, the s16g's and 14b's. Both with internal WG's. They ported and installed a 34mm flapper and said it helped. But Im wondering if when I up the boost
it will go away because Ill have more air pushing through. Humm..... anyone know?



14.5 @ 95mph / 7psi 185hp/180tq :thumbsdown